(a) Field of the Invention
The present invention relates to a double-sided LCD (liquid crystal display) device and, more particularly, to a double-sided LCD device including front and rear LCD panels.
(b) Description of the Related Art
A large number of types of LCD devices have been used in a variety of applications. A double-sided LCD device is one of the types of the LCD devices, having front and rear LCD panels, which are coupled together in a back-to-back fashion. The LCD panels used in the double-sided LCD device generally have the same size and are generally used in the advertisement in a station or on a train.
FIG. 9 shows a conventional double-sided LCD device. The LCD device, generally designated by numeral 200, includes front and rear LCD panels 202, a backlight unit 201 sandwiched therebetween, and a shield frame 203 receiving therein the peripheral portions of the LCD panels 202 and the backlight unit 201. In the exemplified configuration, tape carrier packages (TCPs) 204 each mounting thereon a driver IC (not shown) and an interconnect pattern (not shown) extend linearly from the peripheries of the LCD panels 202 toward circuit boards 205. The driver ICs drive data lines and gate lines in the LCD panels 202.
The basic function of the circuit boards 205 is to electrically couple together the TCPs 204 and external circuits, and thus the circuit boards 205 may be referred to as coupling boards. In some cases, the circuit boards 205 may include therein control circuits and/or power supply circuits for driving the LCD panels 202. The depicted structure has the advantage of a smaller thickness and the disadvantage of a larger peripheral area disposed around the effective display area, due to the TCPs 204 extending linearly.
FIG. 10 shows a sectional view of another conventional double-sided LCD device 200a, described in Patent Publication JP-A-7(1995)-43688. In FIGS. 9 and 10 as well as the following figures, similar constituent elements are designated by similar reference numerals. In the structure depicted in FIG. 10, a pair of LCD modules 210 each including therein an LCD panel 202, TCPs 204 and circuit boards 205 are disposed in a plane symmetry with respect to a central plane passing through the central line of a lamp 206. The TCPs 204 are bent in an L-shaped structure, whereby the circuit boards 205 extends normal to the LCD panels 202 to achieve the advantage of a smaller peripheral area for the LCD panels 202. The LCD device of FIG. 10 has, however, the disadvantage of a larger thickness due to the two circuit boards 205 extending normal to the LCD panels 202 in succession.
FIG. 11 shows another conventional double-sided LCD device 200b, described in Patent Publication JP-A-64(1989)-84292. In the depicted structure, a pair of LCD modules 211 each having a configuration similar to that of FIG. 10 are disposed so that the circuit boards 205 are slightly deviated from one another in the extending direction of the LCD panels 202 to thereby allow the circuit boards 105 to be juxtaposed with each other. This reduces the thickness of the LCD device 200b while achieving a smaller peripheral area.
In the structure of FIG. 11, there is a disadvantage, however, in that the center of the lamp 206 is not aligned with the center of at least one of the LCD panels 202, as understood from FIG. 11. Thus, the distance between the lamp center and one edge of the at least one of the LCD panels 202 is different from the distance between the lamp center and the other edge of the at least one of the LCD panels 202, thereby generating ununiformity of the brightness of the screen of the at least one of the LCD panels 202 to degrade the image quality. In addition, the deviation of the arrangement between the front and rear LCD panels increases the peripheral area for the LCD device.